Regulator



July 2, 1946. T J. PETERSON 2,403,393

- REGULATOR maa April 1s, 194s Figi. Figi.

VARIABLE VOLTAGE PUT VMAx.

VOLTAGE Justin FeJcJeT-som *by Jv/my ZM His Attorney.

Patented -'July 2,l 1946 REGULATOR Justin Peterson, Swampscott, Mass., assignor to General ElectricA Company, a corporation of New York Application April 16, 1943, Serial No. 483,353

1 11 Claims. This invention relates to electrical regulators and more particularly to improvements in static constant current transformers.

By a static constant current transformer is meant an electrical transformer which without the use of moving parts will supply constant output current with substantial variations in input f voltage, or load impedance, or both.

The invention operates on the principle of two linear reactances of opposite sign effectively connected in parallel with each other and in series between the source of current supply and the load.A The volt-ampere characteristics of these linear reactances are parallel so that over a substantial range of voltage the vector sum (arithmetical difference) between their currents is con stant. One reactance is inductive and the linearity of its working range is obtained by magnetic saturation of a restricted portion of an iron core and the substantial linear working range extends between the point of saturation of the restricted section and the point of saturation of the main body of the core. The other reactance is a capacitor.

The invention is characterized by the use of a single magnetic core which by means of properly proportioned windings and flux leakage paths permits the use of a high voltage low current and therefore economical capacitor and also permits the operation at, any desired voltage ratio between the input and the output circuits. This is accomplished by making the leakage reactance of the transformer the inductive reactance of the regulating circuit and by connecting the capacitor into the system by means of coupling windings on the transformer so as effectively to connect it in parallel circuit relation with the transformer leakage reactance.

An object of the invention is to provide a new and improved electrical regulator.

Another obiect of the invention is to provide a novel, compact,l inexpensive and light-weight static constant current transformer. I

The invention will be better understood from the following description taken in connection with lthe accompanying drawing and its scope will be pointed out in the appended claims.

In the drawing Fig. 1 is an embodiment of the invention having a so-calledshell-type core, Fig. 5

f transformer has a 1:1 ratio.

ferent core type of core and a different winding arrangement.

Referring now to the drawing and more particularly to Fig. 1, a shell-type iron core I is shown as provided with flux leakage paths 2. In the legs of these leakage paths are cut windows 3 so that the leakage paths `have restricted sections. Mounted on the center leg of the core on opposite sides of the leakage paths are coils 4 and 5, while an additional coil B is closely coupled to coil 5. 'Coils 4 and 5 have equal numbers of turns and they are connected in series with each other through a-oapacitor l. this series connection being such that the polarities of the coils 4 and l are in opposition. A variable voltage inputcircuit l is connected across a portion of the coil 4 by means of an adjustable tap or slider `8 so that adjustment can be made for changes in the level or average value of the voltage of the input circuit 8. It will thus be seen that the coil 4 is in effect an autotransformer and that therefore it is effectively two windings, one of which is connected between the conductors of circuit 8 and the other of which is connected between its two ends or terminals. l

A constant current load or output circuit i0 is connected across the coil B.

The operation of Fig. 1 may be explained by reference to Fig. 2. In this figure the curve Il is the volt-ampere characteristic of the leakage reactance of the transformer shown in Fig. l. That is to say, the ordinates of the curve Ii represent the voltage difference between the input circuit 8 and the output circuit I0 due to leakage reactance effects if the'circult through the capacitor l were open. In order to eliminate the complication introduced by a voltage ratio other than i it is assumed for purposes of the present explanation that the number of turns of the coil 4 which are connected across the input circuit '8 and which constitute the primary winding of the transformer are equal to the number of turns of the coil i which constitute the secondary winding of the transformer and that consequently this With the circuit through the capacitor open the coil 5 and remaining portion of the coil 4 have no effect on the action. Under these circumstances the ordinates or voltage of the curve li would be the leakage 0 reactance voltage drop in the transformer and the abscissae of the curve would be the load current of the transformer. The bend at the point i2 in the curve il is caused by the magnetic saturatfon of 4the restricted portions of the leakage and Fig. 4 is another modidcation using a dif- 55 paths 2 which are formed by the windows 3.

These windows are in eiect air gaps which are bridged by the restricted portions. The second bend` in the curve I I at I3 occurs when the main body or .portion of the leakage path 2 saturates and, as will be seen, this occurs at substantially higher values of voltage and current than those corresponding to point I2. Between these two points the volt-ampere characteristic of the leakage reactance of the transformer is substantially linear and this is the working range of the regulating action of the invention. Thus, the range of voltage which is consumed by the transformer in its regulating action in maintaining constant .output current with variations in input voltage and variations in load impedance is the difference between the voltages corresponding to points I2 and I3 which are labeled Vmin and Vmax in Fig. 2.

The closing of the circuit of the coils 4 and 5 through the capacitor I in eiect connects the capacitor in parallel or shunt circuit relation wi th the transformer leakage reactance. One way to explain that this is so is as follows: With the output circuit I open, practically all of the flux of the exciting or primary winding will flow through the coils 4 and 5 because the flux path through these coils does not include any restricted section so that its reluctance is lower than that ofthe leakage paths. Under these circumstances the'voltages induced in the coils 4 and 5 are equal and are opposite in their series circuit so that no voltage appears across the terminals of the capacitor. This is, of course, as it should be because with no load current flowing there is no leakage reactance voltage drop through the transformer. If no load current flows in the output circuit I0 the load ampere turns in the primary winding or primary portion of the coil 4 and-in the secondary coil 6 oppose each other; that isto say, they both try to send -flux through the center leg of the core in opposite directions with the result that they both send'ux in the leakage paths 2in the Asame direction. These primary and secondary winding leakage fluxes induce voltages in the coils 4 and 5 which are additive in their series circuit by reason of the fact that the coils are wound in opposite directions or are reversely connected.

The result is that the voltage across the capacitor b tween the points I2 and I3. The 'circuit there-.

fore acts like one having a reactor with a characteristic similar to that of curve II and a capacitor similar to that of curve I2 connected in parallel with each other and in series with the circuit. The result is that over a range of voltage between Vmm and Vmx across the parallel combination of the capacitor and reactor, the difference between the currents in the capacitor and reactor, which corresponds to the resultant current which can get through the parallel combination, will be constant. Thus, as shown in Fig. 2, the horizontal distance between the curves II and I2 over the `working range of the circuits between the points I2 and I3 is a constant show- 4 ing that the difference between the and reactor currents or the resultant current of the system is constant.

In Fig. 3 the core I3 is of the so-called core type and in addition to the two usual legs and interconnecting yokes it has a third leakage leg I4 provided with restricted saturating sections I5. Coils 4 and 5 corresponding to those in Fig. l are mounted on the two coil legs of the core and both these coils constitute autotransformers, the variable voltage input circuit 8 being connected across a portion of the coil 4, as in Fig, l, and the constant current output circuit In being connected across a portion of the coil 5.

That the capacitor l is in fact connected in shunt circuit relation with the leakage reactance of the transformer can perhaps be understood more clearly by assuming in Fig. 3 that the input circuit B and the output circuit I0 are both connected across all of their respective coils 4 and 5 respectively. This corresponds to a 1:1 ratio of transformation for the transformer as a whole and if the capacitor l 'is omitted it will be seen that the transformeris in effect short circuited. In other words, the current from the supply circuit to the load circuit can flow directly through the conductors interconnecting the coils 4 and 5 so that there will be no leakage reactance eiect or voltage drop between the input and output circuits. However, when this connection between the coils is completed through the capacitor, then it is as though the leakage reactance of the transformer were shunted by the capacitor. Obviously, if this is true for the special case of a 1:1 ratio it will also be true for any other ratio transformation so that the input and output circuits may be connected across any desired portions of the windings 4 and 5.

II the operation of Fig. 3 is the same as that of Fig. 1,

1n Fig, 4 the core I3 differs from that of Fig. 3 in that the leakage leg I5 is the center leg and two pairs of coils are mounted on the core, the coils 5 and 6 being on one leg and corresponding to those in Fig. 1 and the coil 4 being on another leg and corresponding to the similarly numbered coil in Fig. l. The fourth coil I6 is mounted on the same leg with the coil 4 and constitutes the primary winding of the transformer.

The operation of Fig. 4 is the same as that of Fig. 1.

From the above description it will be seen that the invention is characterized by the use of two pairs of windings, the windings of each pair heing closely coupled with respect to each other but the two pairs of windings being loosely coupled with respect to each other. However, the two windings' constituting each pair may either be separate coils or may be parts of the same coil depending upon whether the relationship is that of an insulating transformer or an autotransformer and this is a matter of choice. Although the various coils of each pair have been shown mounted side by side on their respective core legs it will be understood that tl' ey may also be mounted concentrically, that is to say, one on top of the other; and this in practice is usually preferable as it is more conducive to close coupling and 10W leakage.

By making the number of turns cf the wind-- capacitor eficaces.

, thus making for the use of an economical size of capacitor.

While there have been shown and described particular embodiments of .this invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the'invention and, therefore, it is aimed inthe appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a transformer having input and output terminals, vmeans for giving said transformer an abnormally high leakage re'actance, a capacitor, and means for impressing across said capacitor a voltage which is proportional to the leakage reactance voltage drop of said transformer, said leakage reactance having a voltampere characteristic corresponding to that of a saturation curve, said capacitor lhaving a voltampere characteristic which is substantially .parallel to the characteristic of said leakage reactance above the knee of said curve.

2. In combination, a variable alternating voltage supply circuit. a constant alternating-current load circuit, a transformer interconnecting said circuits, said transformer having a pair of coils with the same number of turns, a primary winding closely coupled to one of said coils, a secondary winding closely coupled to the other of said coils, said transformer having` a core provided with a normally saturated magnetic shunt for the leakage flux of said coils, a. capacitor, and means for connecting said coils in series with said capacitor in a closed circuit in which the polarities of said coils are in opposition, the volt-ampere characteristic of said capacitor being substantially parallel to and displaced from a portion of the volt-ampere characteristic of the leakage re actance between said coils.

3. In combination, a'magnetic core having two coil receiving sections, two equal coils mounted respectively on said sections, said sections having a common magnetic shunt for their leakage iiux, at least a portion of said shunt being normally magnetically saturated,- exciting means for said core relatively closely coupled to one of said coils, output means relatively closely coupled to the other of said coils, and capacitive means for completing a series connection between said two coils.

4. In combination, a transformer having a continuous magnetic leakage flux path with a saturated restricted section magnetically between all` of the primary winding and all of the secondary winding, a capacitor, and coupling means for impressing across said capacitor a voltage which is proportional tothe leakage reactance voltage drop of1said transformer.

5. In combination, a transformer having a continuous magnetic leakage iiux path with a normally saturated restricted section and a normally unsaturated main portion, a capacitor,l and couings without reducing tliecoupling between the windings of each pair, said leakage path having pere characteristic of the leakage reactance of said transformer,

7. In combination, a transformer having input and output terminals, means for giving said transformer an abnormally high leakage ux, winding means on said transformer having a resultant voltage induced therein which is proportional to the leakage flux of said transformer, and a capacitor connected to said Winding means so as to have said voltage impressed across its terminals, said capacitor having a reactance which is numerically equal to .the ratio of said voltage to the current of said transformer over a predetermined current range.

8. In combination, a transformer having a continuous magnetic leakage ilux path with a saturated restricted section between all of the primary winding and all of the secondary Winding, a. capacitor, and coupling means for energizing said capacitor with a voltage which is proportional to the leakage ux of said transformer..

9. In combination, a transformer having a con" tinuous magnetic leakage iluk path with a normally saturated restricted section and a normally unsaturated mainportion. a capacitor, and at vleast one coupling coil on said transformer for energizingsaid capacitor with a voltage which is proportional to the leakage flux of said transformer, the volt-ampere characteristic of said capacitor being substantially parallel to a predetermined portion of the curve representing the relation between the voltage proportional to said leakage iiux and the transformer' current.

10. In combination, a transformer, a magneticall-y saturable leakage ilux path on said transformer, winding means on said transformer having induced therein a voltage proportional to said leakage iiux, said voltagehaving an over-all nonlinear relation to the transformer current by reason of the saturation of said leakage flux path .and having a substantially linear working range within said over-all non-linear relation. and a capling coils on said transformer for impressing leakage reactance of said transformer.

6. In combination, a transformer having a. magnetic core, two pairs of windings on said core,

.said core having a magnetic leakage path for reducing the coupling between said palrso! windpacitor connected to said winding means so as to have said voltage impressed across its terminals, said capacitor having a linear volt-ampere relation which is substantially parallel to saidlinear working range.

11. In combination, a single magnetic core, a

pair of equal coils mounted on said core, a leak- -age 'flux path with a. magnetically saturable restricted section for decoupling said coils and proi '.coils, a capacitor, said coils and capacitor being serially connected in a closed circuit in which the induced voltages of said coils are in opposition,

said capacitor having a linear reactance whose volt-ampere characteristic is substantially parallel to the substantially linear working range 0I said leakage reactance. i

J UBTIN PETERSON. K 

